DESCRIPTION: The study proposes to examine the potential role of the perireceptor event, amino acid transport, in modulating the chemosensation of amino acids in the spiny lobster. Potentially, the removal of amino acids from the receptor environment by transporters could impact on the sensory acuity of the olfactory system, but current data suggest that the transport Vmax is too low to significantly affect amino acid concentrations at the receptor. Using the techniques of transporter and second messenger biochemistry the investigator will address three issues. First he will determine if certain amino acid odorants can up-regulate the removal of amino acids from the receptor environment. This will be done by measuring the rate of transport of glycine into the cellular compartment of olfactory sensilla in the presence or absence of a single amino acid (or mixtures) via standard rapid filtration assays. Secondly, the investigator will assess whether or not the second messengers typically generated by amino acid odorants can, in and of themselves, affect the rates of olfactory amino acid transport. These experiments will measure amino acid transport in the presence of either membrane permeant analogs of intracellular messengers (e.g., 8-bromo-cAMP) or compounds that directly affect concentrations of intracellular messengers in a lasting manner (e.g., forskolin). Finally, the role of phosphorylation or dephosphorylation of olfactory plasma membrane proteins in affecting amino acid clearance from the receptor environment will be addressed by experiments examining the effect on glycine uptake after tissue treatments with compounds that directly affect protein phosphorylation (e.g., phorbol ester, or okadaic acid).